<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<script>
function foo()
{
  var newTable = document.createElementNS("http://www.w3.org/1998/Math/MathML", "mtable")

  document.getElementById("mtr").appendChild(newTable);
}
</script>
</head>

<body onload="foo()">


<div>
  <math xmlns="http://www.w3.org/1998/Math/MathML" display="block">
    <mtable>      <mtr id="mtr">         <mtd>
           <mi>x</mi>
         </mtd>      </mtr>    </mtable>  </math>
</div>


</body>

</html>